NAM is the ISO 3166 country code for Namibia, formerly Southwest Africa.
Namibia is often called Nam (rhymes with ham) by South Africans.
Firstly because it is a reasonable abbreviation.
Secondly because all cars from Namibia sport a sticker with this country code.
And lastly as a joke, for the parallels with Vietnam. The Apartheid South African Government fought an eventually futile war against SWAPO - communist, soviet-backed terrorists er... freedom fighters in Namibia in the 1980s.